I'm sure everyone here who's ever played the original Doom games (1 and 2, not the mods and whatnot) noticed the soundtrack is practically ripping off real songs. This thread will be used to fill in the complete soundtrack and find out which songs are actually original works and which are just taken from other pieces.
http://www.doomworld.com/linguica/doomcovers/

DOOM
E1M1
Metallica - No Remorse or Master of Puppets (lots of debate on this one)

E1M2


E1M3


E1M4
Pantera - Rise

E1M5


E1M6


E1M7


E1M8


E1M9 (and all other hidden levels)


E2M1
AC/DC - Big Gun

E2M2
Metallica - The Call of Ktulu

E2M3
Pantera - Regular People


E2M4


E2M5


E2M6


E2M7


E2M8


E3M1
Pantera - Mouth For War

E3M2


E3M3
Slayer - Behind The Crooked Cross

E3M4


E3M5


E3M6


E3M7


E3M8
Slayer - Silent Scream

(The fourth episode added in The Ultimate Doom reuses the soundtrack from the rest of the game).


DOOM II
If I remember correctly, Doom II reuses some songs throughout the game's 30 maps, so I'm not gonna bother listing these in any order.

Map07
Slayer - South Of Heaven

Map10
Black Sabbath - After All (The Dead)

Map18
Pantera - This Love

Map23
Alice In Chains - Them Bones

Map25
Alice In Chains - Angry Chair